U.S. Pat. No. 3,695,096 discloses connection pins fitted with strain gauges for installing in the end fittings of two elements for interconnection in order to measure the force to which said elements are subjected when one of them is loaded and stresses the connection pin.
In particular, in the field of aircraft brakes, it is known to fit strain gauges to the dog for taking up torque from a brake or to the connection pin for connecting a bar to take up torque from the associated brake in order to determine the shear force to which the dog is subjected or to which the pin is subjected during braking, and thus measure the braking torque developed by said brake.
U.S. Pat. No. 4,474,060 discloses a ring fitted with strain gauges that is installed in one of the fittings that receive the connection pin of the bar for taking up the torque of the associated brake. The ring has a special shape that leads to measurable deformation of its wall under the effect of a load stressing the connection pin.
With both of those techniques, the wide variety of brake sizes leads to the pins or the rings being dimensioned specifically for each brake.